1. Field of the Invention
2. Discussion of the Background
The invention relates to an insulating glazed element comprising at least two glass sheets separated from each other by a space and at least one support element, especially for a refrigerated enclosure.
Glazing panels are generally placed in a frame making it possible to support them for the purpose of their use in fields where their thermal insulation properties are sought (building, refrigeration, etc.).
It is well known that when a cold wall is in contact with hot and moist air, the wall becomes covered with water from the condensation of the ambient water vapor, it being possible for this water even to become transformed into frost if the temperature is low enough. More specifically, it is when the temperature of the wall is less than the dew point of the ambient air that condensation is produced. In the case of glazing panels, the condensation may appear on the glass and also on the frame which supports the glazing panel, particularly if it is metallic and therefore capable of forming a thermal bridge.
The main feature of the means which have been proposed to overcome the drawbacks associated with the appearance of condensation and with the formation of frost relates to limiting heat exchanges between the walls of the glazing panel. It has thus been proposed to use insulating glazing panels, formed by the superposition of glass sheets separated from each other by a layer of air or by a space kept under vacuum, and to heat them over the entire surface of the glass by means of an electrically conductive layer (EP-A-0 314 477, U.S. Pat. No. 3,655,939 and FR-A-2 769 337) or of metal wires supplied with electric current (CA-A-885052).
The problem of condensation and of frost mentioned above appears more specifically in the field of refrigeration at relatively low temperature used especially for the preservation of frozen food items.
It is usual for frozen food items to be offered for sale by displaying them in freezers which are open at the top (or chest freezers), the front face and/or at least one side face of which is(are) glazed. This method of displaying the food items has two advantages:    the first advantage is that it is possible, even at a distance, to quickly select the type of food sought because of the transparency of the front face,    and the second advantage is that it is easy to grab hold of the article which is finally chosen since the freezer is permanently open in its upper part.
With chest freezers, and in spite of the use of insulated glazing, there is still the problem of condensation or of frost at the periphery of the glazed surface. Because of their exposure to cold, the outside of the perimeter of the glazing, which is less insulated than the rest of the glazed surface, and of the elements supporting the glazing are at a lower temperature than that of the ambient air, which generates condensation both on the glass and on the support.
The presence of condensation water or of frost has drawbacks: reduction in the field of vision through the glazed element, appearance of mold, formation of puddles on the ground, transfer of moisture to the skin, the presence of stains on the clothing, the risk of the skin “sticking” to the frosted parts, etc.
To overcome these drawbacks, it is known to heat the glazed element by means of a peripheral metal bead concealed in the frame supporting the glazed wall. However, this bead is not entirely satisfactory:    it is minimally adjustable because its length depends entirely on the dimension of the glazing,    it is tricky and expensive to implement because it is necessary to make a perfectly gaged groove in the thickness of the seal of the glass sheets,    since the contact area between the bead and the frame is small, the heating efficiency is low, and    given that it is fed by an electric current of high voltage (about 220 volts), a safety device, which breaks the circuit in the case of accidental breakage of the glass, must absolutely be combined therewith.